Refer to this question. It's homework, and clearly disclosed as such. Somebody flagged the question, stating "I'm assuming homework questions aren't allowed here."
Got me thinking that we haven't actually established a clear policy on homework questions.
UPDATE: Here's a more recent occurrence and perhaps better example where the question, IMHO, is apropos to personal finance, but it is being voted-to-close because it is homework: Solving for mortgage payment amount and its deduction on the total principal?
Should homework questions be permitted on the site? If yes, under what circumstances? If no, why not?